Jetpack

This is a comprehensive plugin that contains a wide range of features: notifications in your toolbar, connect site to social networks and automatically share, view concise stats, allow subscriptions to your posts to receive notifications, share content with Facebook, Twitter and more.

Contact Form 7

With Contact Form 7 you can easily create instant drop in forms for the visitors of your WordPress blog. This way you will be able to stay in touch with them without providing your email address. Your readers can contact you any time and your email remains spam-free.

All in One SEO Pack

This is a plugin that helps you optimize your WordPress for SEO and generates meta tags automatically, optimizes titles, avoids duplicate content, includes Google Analytics support. It is the only plugin to provide SEO integration for e-commerce.

WP Security Audit Log

This plugin enables you to keep track of all the WordPress users activity and everything else that is happening under the hood of your WordPress to ensure user productivity and to help you identify WordPress security issues before they become a security problem. With WP Security Audit Log you can also configure specific monitoring rules so when a specific change happens you are instantly alerted via email of such change.